AGING AND GAIT Flashcards
Aging and Postural control
-over 65 yo: 1 of 3 experience a fall per year
—>falls are leading cause of injury deaths
—>falls are leading cause of disability and decreased independence
-20-30% sustain injury that reduces mobility
Why do falls increase as we age?
-decreases in cognitive function, sensory function, and motor function
-if all three of these functions decrease below a certain threshold –> much greater fall risk (functional limitation threshold)
-may see falls earlier on if you have a challenging task and/or environment that challenges cognition
-a combination of factors contribute to increase in falls as we age: disease, environment, genetics
Skeletal changes in bone with aging:
*Shape and density altered with the balance of resorption and formation of bone
*Decline in bone mass with age
*Decreased tolerance for stress
*Altered joint motion- due to changes in joint surfaces
Joint changes with age
-decreased ROM at most joints
-active decreased more than passive due to ms. tendon unit
-increased stiffness due to viscoelastic changes –> changes in water content (more stress for certain level of strain)
-passive ROM may be limited due to stiffness
-greater demand moments are required for movement
Muscular changes with age:
sarcopenia: Age- associated decline in muscle mass due to total number of fibers decreasing
-begins at age 30
-gradual loss of muscle mass from 30-50 yr
-30% loss from 50-80 years
How does muscle change with age when torque (moment) production is normalized to the cross-sectional area or mass?
small age-related decrement remains
-there is a general increase in weakness that occurs with aging
Neuromuscular changes with aging:
OLDER ADULT CHANGES:
-initially lower number of fibers recruited
-fiber recruitment variable over time
-can achieve same levels of firing with practice
-proximal recruitment greater than young adults
-distal recruitment in older adults is less compared to younger
-decreased CSA of type II (fast twitch)> type I (slow twitch) –> more a blend of type I and II
-increased co-activation of mm. may lead to decreased effective moment production –> decreased efficiency of gait (have to produce more force to achieve same gait speed)
Strength, power, and endurance changes with aging:
STRENGTH: Declines 10-15% per decade after fifth decade
POWER: moment * angular velocity
-declines similar to strength
-more closely correlated with functional ability
-loss appears earlier than strength and more rapid decline
Sensory changes with age
SOMATOSENSORY
* Decreased proprioception, tactile sensitivity, vibration sense
(peripheral neuropathy)
VISION
* Decreased acuity, visual threshold (light needed), and contrast
sensitivity
VESTIBULAR
* Decreased hair and nerve cells
changes in older adult gait
-dec. gait speed
–> if ankle PFs are more weak: step length decreases
-dec. stride length: to reduce loading force through the limb, to decrease SL support time
-dec. SLS time
-altered joint kinematics (ankle largest)
-increased step width variability
-increased energy expenditure
What is the typical range for gait speed from ages 20-59?
1.35-1.4 m/s
What spatiotemporal aspect of gait does not change much in older adults?
cadence- step frequency
steps taken/minute
Kinematics at each joint change with age–> why is this important?
change in kinematics is expected with change in speed
kinematic change at the same speed is what is important
Change in joint kinematics with age
-hip extension reduced with age (38% decrease)
-knee motion stays relatively the same with age
-ankle plantarflexion motion decreases with age
-ankle DF decreases about 43%
-more anterior pelvic tilt in older adults
Older adults have to expend more energy to walk at the same _____ as younger adults
speed
